The Codex is one of the three maps where you can use your mount in the warfront. There are 4 main capture points, being The Codex, Thontic Statue, Translation Scope, and The Vault. In order to win, you have to reach 1000 points, which are gained through controlling points or killing players.
Points are divided up into three main groups. The first being killing enemy players, which award 2 points per kill. The second, is by controlling The Vault, Thontic Statue, or Translation Scope. Each of these gives 3 points per tick. The Codex gives 5 points a tick. The time it takes to capture a point from neutral is 10 seconds on your side, and 30 seconds if you are capturing the enemy neutral point.
If you are stealing an objective from the enemy team, keep in mind that it takes 30 seconds to successfully capture it. If the enemy grabs that said point during those 30 seconds, it immediately reverts to whomever controlled it before. If an objective that is controlled is being switched over to the other team though, that objective does not reward any points during the ticks.
The standard method that you would probably see in most fights is that team A and team B would grab their side's objective, then do a free-for-all at the Codex to grab it. Don't do this. Instead, forget about the Codex and designate one person from the start to grab the Vault and another person to grab your objective. (Depending on the side, it can either be scope or statue). The rest of the team would then go to either the statue or scope, depending on which side you are on and grab it within the 10 second window of first time enemy capture.
Why should you do this? Because by the time you are 30 seconds in, you would have successfully grabbed 3 points, giving you 9 points a tick for every 5 that the Codex gives. Plus -- and this is important -- you will force the enemy team who is gathered at the Codex to split and try to grab the other three objectives. When that happens, and it always will because you can't win the match with just one objective alone, you should zerg (rush) the point, and with superior numbers you will win and grab it.
In the mean time, you can send one or two of your team members to protect your points, and eventually push the fight to their respawn point. If you do this, and grab a 200 point lead, then even at 850 points if you lose all but 1 objective, you will still win.
You can also find 4 buffs around the map, one behind The Codex, Scope, and Statue which would boost your damage, and another at The Vault that will boost your movement speed. These boosts can be picked up if you are invisible and won't force you to de-cloak.
The ideal group is to a split between high CC members and single target DPS. For every 3 DPS, you should have 1 healer and 1 support of each type. If you get 3 bards, then the skills will overlap each other and you won't gain any benefits. If it isn't possible to get different supports, then it will be better to switch to DPS.
Ideally, you should also have at least one rogue assassin, who would sit under the rocks at the Codex. If you can hold that point, which is next to the water, with a tracking vial you can keep tabs of the entire enemy team's movements, and report that information to the team.